Organic light emitting diode display device and display panel thereof

ABSTRACT

An organic light emitting diode (OLED) display device and a display panel thereof are provided. The organic light emitting diode display panel comprises a first substrate, a first electrode, an organic light emitting layer, a second electrode, and a second substrate. The first electrode is disposed on the first substrate. The organic light emitting layer is disposed on the first electrode. The second electrode is disposed on the organic light emitting layer. The second substrate is located on the second electrode. The material of the second electrode comprises an alkaline earth element and silver. The second electrode comprises a first portion and a second portion, and the first portion is located between the second portion and the first substrate. The ratios of the alkaline earth element to silver in the first portion and in the second portion are different.

This application claims the benefit of People's Republic of Chinaapplication Serial No. 201210472034.1, filed Nov. 20, 2012, the subjectmatter of which is incorporated herein by reference.

BACKGROUND

1. Technical Field

The invention relates in general to an organic light emitting diodedisplay device and a display panel thereof, and particularly to theorganic light emitting diode display device and the display panelthereof comprising an electrode having two portions, wherein the ratiosof an alkaline earth element to silver in the two portions aredifferent.

2. Description of the Related Art

Along with the advances of display technology, various types of displaydevices have been developed. Organic light emitting diode displaydevices have become one of the most important research targets ofdisplay technology due to light weights, good display properties, andlow costs. Therefore, the requirements to the functions andcharacteristics of organic light emitting diode display devices havegradually increased as well.

Generally, the organic light emitting diode structure of an organiclight emitting diode display device is mainly comprised of twoelectrodes and an organic light emitting layer disposed between the twoelectrodes. When a voltage is applied on the two electrodes, chargecarriers are produced and pass through the organic light emitting layer,and the charge carriers combined produce lights.

However, the electrodes located inside the organic light emittingdisplay device is formed on the light emitting layer made of organicmaterials. The reliability and luminous efficiency of the whole displaydevice may be influenced due to the poor adhesion between the electrodesand the organic light emitting layer. Therefore, researchers have beenworking on providing an organic light emitting diode display device withhigh reliability and great luminous efficiency.

SUMMARY

The invention relates to an organic light emitting diode display deviceand a display panel thereof. In the organic light emitting diode displaypanel, with an electrode having two portions, wherein the ratios of analkaline earth element to silver in the two portions are different,luminous efficiency can be increased, the adhesion between theelectrodes and an organic light emitting layer is improved, and theconductivity of the electrodes are increased.

According to an aspect of the present disclosure, an organic lightemitting diode (OLED) display panel is provided. The organic lightemitting diode display panel comprises a first substrate, a firstelectrode, an organic light emitting layer, a second electrode, and asecond substrate. The first electrode is disposed on the firstsubstrate. The organic light emitting layer is disposed on the firstelectrode. The second electrode is disposed on the organic lightemitting layer. The second substrate is located on the second electrode.The material of the second electrode comprises an alkaline earth elementand silver. The second electrode comprises a first portion and a secondportion, and the first portion is located between the second portion andthe first substrate. The ratios of the alkaline earth element to silverin the first portion and in the second portion are different.

According to another aspect of the present disclosure, an organic lightemitting diode display device is provided. The organic light emittingdiode display device comprises a case and an organic light emittingdiode display panel. The organic light emitting diode display panel isdisposed in the case. The organic light emitting diode display panelcomprises a first substrate, a first electrode, an organic lightemitting layer, a second electrode, and a second substrate. The firstelectrode is disposed on the first substrate. The organic light emittinglayer is disposed on the first electrode. The second electrode isdisposed on the organic light emitting layer. The second substrate islocated on the second electrode. The material of the second electrodecomprises an alkaline earth element and silver. The second electrodecomprises a first portion and a second portion, and the first portion islocated between the second portion and the first substrate. The ratiosof the alkaline earth element to silver in the first portion and in thesecond portion are different.

The above and other aspects of the disclosure will become betterunderstood with regard to the following detailed description of thenon-limiting embodiment(s). The following description is made withreference to the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows an explosion diagram of an organic light emitting diodedisplay device according to an embodiment of the present disclosure;

FIG. 2 shows a schematic diagram of the organic light emitting displaypanel according to an embodiment of the present disclosure;

FIG. 3 shows an organic light emitting diode display panel according toanother embodiment of the present disclosure;

FIGS. 4A-4C illustrate a process for manufacturing an organic lightemitting diode display panel according to an embodiment of the presentdisclosure; and

FIGS. 5A-5B illustrate a process of an organic light emitting diodedisplay panel according to another embodiment of the present disclosure.

DETAILED DESCRIPTION

In the embodiments of the present disclosure, an organic light emittingdiode display device and a display panel thereof are provided. In theorganic light emitting diode display panel, with an electrode having twoportions, wherein the ratios of an alkaline earth element to silver inthe two portions are different, luminous efficiency can be increased,the adhesion between the electrodes and an organic light emitting layeris improved, and the conductivity of the electrodes are increased. Thefollowing embodiments are for the purpose of elaboration only, not forlimiting the scope of protection of the invention. Detailed structuresand processes may be modified or changed by one skilled in the art afterhaving the benefit of this description of the disclosure.

Referring to FIG. 1, FIG. 1 shows an explosion diagram of an organiclight emitting diode display device 10 according to an embodiment of thepresent disclosure. As shown in FIG. 1, the organic light emitting diodedisplay device 10 comprises an organic light emitting display panel 100,a case 200, and a front plate 300. The organic light emitting displaypanel 100 is disposed in the case 200. The organic light emittingdisplay panel 100 is connected to driving units (not shown) forreceiving driving signals. The front plate 300 is also disposed in thecase 200. The front plate 300 is located between the organic lightemitting display panel 100 and observers. The front plate 300 being atransparent cover plate can provide protection, resistance to pressure,and stain resistance. The front plate 300 can further comprisefunctional structures, such as touch sensors, or barriers or lens forthree-dimensional displaying. In the embodiment, as shown in FIG. 1, thecase 200 comprises an upper case 200A and a lower case 200B. The organiclight emitting display panel 100 and the front plate 300 are disposedbetween the upper case 200A and the lower case 2003. In otherembodiments, the front plate 300 can be removed.

Referring to FIG. 2, FIG. 2 shows a schematic diagram of the organiclight emitting display panel 100 according to an embodiment of thepresent disclosure. As shown in FIG. 2, the organic light emittingdisplay panel 100 comprises a first substrate 110, a first electrode120, an organic light emitting layer 130, a second electrode 140, and asecond substrate 150. The first electrode 120 regard as anode isdisposed on the first substrate 110 and is located between the firstsubstrate 110 and the second substrate 150. The organic light emittingdisplay panel 100 may further comprise additional structures, such asthin film transistors (TFT), conductive lines, capacitors, dielectriclayers, pixel definition layers, and etc., between the first substrate110 and the first electrode 120, and the description of those structuresand the driving operations thereof are omitted herein. The organic lightemitting layer 130 is disposed on the first electrode 120 and is locatedbetween the first electrode 120 and the second substrate 150. Theelectrodes on two sides of the organic light emitting layer 130 regardas cathode and anode to produce electron-hole pairs with a voltageapplied thereon, and the electrons and holes combine in the lightemitting layer for emitting lights. The second electrode 140 is disposedon the organic light emitting layer 130 and is located between theorganic light emitting layer 130 and the first electrode 120. There isusually a gap between the second substrate 150 and the second electrode140; however, the second substrate 150 and the second electrode 140 canalso be contacted to each other. A capping layer (not shown) can furtherbe disposed on the second electrode 140 to fully cover the firstelectrode 120, the organic light emitting layer 130, and the secondelectrode 140 for preventing water and oxygen from passing through, suchthat the life of the organic light emitting diodes can be prolonged. Thefirst substrate 110 and the second substrate 150 can be sealed withencapsulating materials, such as frits (not shown) or sealants (notshown) connecting the first substrate 110 and the second substrate 150for enclosing a space, in which space the organic light emitting diodesare disposed. Further, an optical cement adhesive (OCA, not shown) canbe filled in the space and occupy part of the space where the organiclight emitting diodes do not occupy, such that chances of the organiclight emitting diodes being damaged under pressure are reduced. Thematerials of the first substrate 110 and the second substrate 150 can beglass, plastics, acrylates, ceramics, metals, or the composite structurethereof. The substrate (either the first substrate 110 or the secondsubstrate 150) disposed on the light emitting surface needs to be lighttransmissive.

In the embodiment, the material of the first electrode 120 comprises atransparent conductive material, such as indium tin oxide (ITO), andsilver for aluminum), and indium tin oxide and silver form a compositestacked structure, such as ITO-Ag-ITO. In the structure, silver canreduce resistance and can be used as a reflective layer. When the firstelectrode 120 is located on the light emitting surface, the thickness ofthe silver layer needs to be controlled in order for lights to passthrough. The material of the second electrode 140 comprises an alkalineearth element and silver (aluminum may apply as well). In thisembodiment, the second electrode 140 is located on the light emittingsurface; therefore, the thickness of the second electrode needs to becontrolled in order for lights to pass through. The second electrode 140comprises a first portion 141 and a second portion 143, the ratios ofthe alkaline earth element to silver in the first portion 141 and in thesecond portion 143 are different. In the embodiment, as shown in FIG. 2,the first portion 141 of the second electrode 140 is such as locatedbetween the second portion 143 of the second electrode 140 and the firstsubstrate 110. In one embodiment, as shown in FIG. 2, the interface 140a between the first portion 141 and the second portion 143 has such asan irregular shape. In another embodiment, the interface between thefirst portion 141 and the second portion 143 can also be flat (notshown), and the first portion 141 and the second portion 143 are twostacked planar films.

In the embodiment, the organic light emitting layer 130 comprises suchas electron transport layer (ETL)/electron injection layer (EIL),emission layer (EML), and hole transport layer (HTL)/hole injectionlayer (HIL). The emission layer is disposed between the electrontransport layer/electron injection layer and the hole transportlayer/hole injection layer (not shown).

In the embodiment, the material of the electron transport layer and thematerial of the electron injection layer comprise, for example, BPhen(4,7-diphenyl-1,10-phenanthroline), Liq(8-hydroxyquinolinolato-lithium), BALq(Bis(2-methyl-8-quinolinolate)-4-(phenylphenolato)aluminium), TPBi(2,2′,2″-(1,3,5-benzinetriyl)-tris(1-phenyl-1-H-benzimidazole), or thecombinations thereof. The material of the electron injection layerfurther comprises lithium (Li) or cesium (Cs) dopants. In theembodiment, the material of the hole transport layer comprises, such as,NPB (N,N′-bis(naphthalen-1-yl)-N,N′-bis(phenyl)-benzidine), TPD(N,N′-bis(3-methylphenyl)-N,N′-bis(phenyl)-benzidine), α-NPD(N,N′-bis(naphthalen-1-yl)-N,N′-bis(phenyl)-2,2′-dimethylbenzidine), orthe combinations thereof. In the embodiment, the material of the holeinjection layer comprises, such as, HAT-CN(Dipyrazino[2,3-f:2′,3′-h]quinoxaline-2,3,6,7,10,11-hexacarbonitrile),phthalocyanine copper complex (CuPC), F4-TCNQ(2,3,5,6-tetrafluoro-7,7,8,8-tetracyano-quinodimethane), or thecombinations thereof.

In the embodiment, the material of the light emitting layer may comprisefluorescence materials or phosphor materials of red light, green light,or blue light. The red fluorescence material comprises such as a mixtureof rubrene and Alq₃ (Tris(8-hydroxy-quinolinato)aluminium) as the hostmaterial doped with DCJTB dye(4-(dicyanomethylene)-2-tert-butyl-6-(1,1,7,7-tetramethyljulolidin-4-yl-vinyl)-4H-pyran)as the guest material. The red phosphor material comprises such as CBP(4,4′-bis(carbazol-9-yl)biphenyl) and/or TCTA(4,4′,4″-Tris(carbazol-9-yl)triphenylamine) as the host material dopedwith Ir(piq)₃ (Tris(1-phenylisoquinoline)iridiurn(III)) and/orIr(btp)₂(acac)(Bis(2-benzo[b]thiophen-2-yl-pyridine)(acetylacetonate)iridium(III)) asthe guest material. The green fluorescence material comprises such asTPBA (2,2′-bi(9,10-diphenyl-anthracene) as the host material doped withC545T(10-(2-Benzothiazolyl)-2,3,6,7-tetrahydro-11,7,7-tetramethyl-1H,5H,11H-(1)benzopyropyrano(6,7-8-l,j)quinolizin-11-one)as the guest material. The green phosphor material comprises such as CBP(4,4′-bis(carbazol-9-yl)biphenyl) and/or TCTA(4,4′,4″-Tris(carbazol-9-yl)triphenylamine) as the host material dopedwith Ir(ppy)₃ (Tris(2-phenylpyridine)iridium(III)) and/or Ir(ppy)₂(acac)(Bis(2-phenylpyridine)(acetylacetonate)iridium(III)) as the guestmaterial. The blue fluorescence material comprises such as MADN(2-methyl-9,10-bis(naphthalen-2-yl)anthracene) as the host materialdoped with DPVABi (4,4′-bis[4-(di-p-tolylamino)styryl]biphenyl) as theguest material. The blue phosphot material comprises such as MCP(1,3-bis(carbazol-9-yl)benzene) and/or UGH-2(1,4-bis(triphenyisilyl)benzene) as the host material doped with FIrPic(Bis(3,5-difluoro-2-(2-pyridyl)phenyl-(2-carboxypyridy)iridium(III))and/or FIr₆(Bis(2,4-difluorophenylpyridinato)tetrakis(1-pyrazolyl)borateiridium(III)) as the guest material.

In the embodiment, the first portion 141 of the second electrode 140 hasa first thickness T1, and the second portion 143 of the second electrode140 has a second thickness T2. The above-mentioned thicknesses are theaverage thicknesses of the corresponding portions. The ratio of thefirst thickness T1 to the second thickness T2 is, for example,1:0.5-1:4.

In an embodiment, the ratio of the alkaline earth element to silver inthe first portion 141 is larger than the ratio of the alkaline earthelement to silver in the second portion 143.

In an embodiment, the alkaline earth element is such as magnesium orsilver.

In an embodiment, the first portion 141 is formed of magnesium, and thesecond portion 143 is formed of silver. In another embodiment, the firstportion 141 is formed of magnesium, and the second portion 143 is formedfrom magnesium and silver. In a further embodiment, the first portion141 is formed from magnesium and silver, and the second portion 143 isformed of silver. In yet another embodiment, the first portion 141 isformed from magnesium and silver, and the second portion 143 is formedfrom magnesium and silver.

The lowest unoccupied molecular orbital (LUMO) of the electron transportlayer/electron injection layer of the organic light emitting layer 130has a band gap (energy gap) value of 2.5-3.5 eV, the work function ofmagnesium is 3.46 eV, and the work function of magnesium-silver alloy ifabout 3.7 eV. In the embodiment, when the ratio of magnesium to themixture of magnesium and silver in the first portion 141 is larger thanthat in the second portion 143, the electron transport layer/electroninjection layer of the organic light emitting layer 130 is in directcontact with the first portion 141 of the second electrode 140, and thework function of magnesium is close to the work function (band gapvalue) of the electron transport layer/electron injection layer, themagnesium content being relatively high in the first portion 141 isadvantageous to the transport or injection of electrons, and hence theluminous efficiency is improved.

In addition, the adhesion between pure magnesium and organic films ispoor. In the embodiment, the material of the second electrode 140comprises magnesium and silver, and the existence of silver isbeneficial to the adhesion between the second electrode 140 and theorganic light emitting layer 130. Moreover, when the size of the organiclight emitting diode display panel is relatively large, the wavepatterns of driving signals from ends of conductive lines tend to decaymore quickly. The existence of silver can increase the conductivity ofthe second electrode 140, and therefore, the undesired changes of thewave patterns of driving signals are reduced.

In the embodiment, when the first portion 141 is formed from magnesiumand silver, the atomic ratio of magnesium to the mixture of magnesiumand silver is about between 80% and less than 100%(100%>Mg/(Mg+Ag)≧80%). Preferably, the atomic ratio of magnesium to themixture of magnesium and silver is about between 90% and less than 100%(100%>Mg/(Mg+Ag)≧90%).

In the embodiment, when the second portion 143 is formed from magnesiumand silver, the atomic ratio of magnesium to the mixture of magnesiumand silver is about between larger than 0% and 90% (90%≧Mg/(Mg+Ag)>0%).Preferably, the atomic ratio of magnesium to the mixture of magnesiumand silver is about between larger than 0% and 80% (80%≧Mg/(Mg+Ag)>0%).

Referring to FIG. 3, FIG. 3 shows an organic light emitting diodedisplay panel 100′ according to another embodiment of the presentdisclosure. As shown in FIG. 3, the difference between the presentembodiment from the embodiment as shown in FIG. 2 is that, the secondelectrode 140 of the organic light emitting diode display panel 100′further comprises a third portion 260. The third portion 260 is locatedon the second portion 143. The third portion 260 is located between thesecond portion 143 and the second substrate 150. The material of thethird portion 260 is silver. In the embodiment, when the first portion141 and the second portion 143 are both formed from magnesium andsilver, the silver in the third portion 260 can enhance the electrontransport/injection properties of the whole electrode. When the materialof the second portion 143 is silver, the third portion 260 can beoptionally omitted. The elements in the present embodiment sharing thesame labels with those in the previous embodiments are the sameelements, and the description of which is omitted.

The embodiments disclosed below are for elaborating the manufacturingmethods of the organic light emitting diode display panel 100 of thedisclosure. However, the descriptions disclosed in the embodiments ofthe disclosure such as detailed manufacturing procedures are forillustration only, not for limiting the scope of protection of thedisclosure. Detailed structures and processes may be modified or changedby one skilled in the art after having the benefit of this descriptionof the disclosure. Referring to FIGS. 4A-4C, FIGS. 4A-4C illustrate aprocess for manufacturing an organic light emitting diode display panelaccording to an embodiment of the present disclosure.

Referring to FIG. 4A, the first substrate 110 is provided, the firstelectrode 120 is formed on the first substrate 110, and the organiclight emitting layer 130 is formed on the first electrode 120. Thedetailed description of processes of manufacturing additionalcomponents, such as thin film transistors and conductive lines, areomitted from the description of the above-mentioned steps.

Referring to FIG. 4B, the second electrode 140 is formed on the organiclight emitting layer 130. In the embodiment, the second electrode 140 isformed by such as a thermal evaporation process. In the embodiment, thefirst portion 141 and the second portion 143 of the second electrode 140are formed in the same thermal evaporation process simultaneously. Theratios of the alkaline earth element to silver in the first portion 141and in the second portion 143 are different.

In the embodiment, the first portion 141 and the second portion 143 areformed in the same thermal evaporation process. When the silver contentin the first portion 141 is higher, in other words, the silver contentsin the first portion 141 and in the second portion 143 are closer, theinterface 140 a between the first portion 141 and the second portion 143is more indefinite and less distinct, that is to say, the physicalinterface that can be observed by such as an electron microscopy is lessclear. Nevertheless, for example, the first portion 141 and the secondportion 143 are two stacked films, an area of the first portion 141close to the organic light emitting layer 130 and an area of the secondportion 143 close to the second substrate 150 still have differentratios of the alkaline earth element to silver.

Referring to FIG. 4C, the second substrate 150 is disposed on the secondsubstrate 150. As such, the organic light emitting diode display panel100 as shown in FIG. 40 (FIG. 2) is formed.

FIGS. 5A-5B illustrate a process of an organic light emitting diodedisplay panel according to another embodiment of the present disclosure.Please refer to FIG. 4 and FIGS. 5A-5B.

First, the structure as shown in FIG. 4A is formed. Next, as shown inFIG. 5A, the first portion 141 of the second electrode 140 is formed onthe organic light emitting layer 130. In the embodiment, the firstportion 141 of the second electrode 140 is formed by such as a thermalevaporation process. The magnesium content in the first portion 141 isrelatively high, and thus, an irregular structure as shown in FIG. 5Amay be formed, and the first portion 141 has a surface of an irregularshape.

Next, as shown in FIG. 5B, the second portion 143 of the secondelectrode 140 is formed on the first portion 141. In the embodiment, thesecond portion 143 of the second electrode 140 is formed by such as athermal evaporation process. The silver content in the second portion143 is relatively high, and thus, the film formation is greater, suchthat the second electrode 140 can be formed with a flat surface.Moreover, the adhesion between the second electrode 140 and the organiclight emitting layer 130 is increased.

Next, as shown in FIG. 4C, the second substrate 150 is disposed on thesecond electrode 140. As such, the organic light emitting diode displaypanel 100 as shown in FIG. 2 is formed.

While the disclosure has been described by way of example and in termsof the exemplary embodiment(s), it is to be understood that thedisclosure is not limited thereto. On the contrary, it is intended tocover various modifications and similar arrangements and procedures, andthe scope of the appended claims therefore should be accorded thebroadest interpretation so as to encompass all such modifications andsimilar arrangements and procedures.

What is claimed is:
 1. An organic light emitting diode display panel,comprising: a first substrate; a second substrate; a first electrodedisposed between the first substrate and the second substrate; anorganic light emitting layer disposed between the first electrode andthe second substrate; and a second electrode disposed between theorganic light emitting layer and the second substrate, the secondelectrode comprising a first portion and a second portion, the firstportion is located between the second portion and the first substrate,wherein an irregular interface is located between the first portion andthe second portion, the material of the second electrode comprises analkaline earth element and silver, and the ratios of the alkaline earthelement to silver in the first portion and in the second portion aredifferent.
 2. The organic light emitting diode display panel accordingto claim 1, wherein the alkaline earth element comprises magnesium (Mg)and calcium (Ca).
 3. The organic light emitting diode display panelaccording to claim 2, wherein the first portion is formed of magnesium.4. The organic light emitting diode display panel according to claim 2,wherein the first portion is formed from magnesium and silver, andmagnesium is between 80% and less than 100%.
 5. The organic lightemitting diode display panel according to claim 2, wherein the firstportion is formed from magnesium and silver, and magnesium is between90% and less than 100%.
 6. The organic light emitting diode displaypanel according to claim 2, wherein the second portion is formed frommagnesium and silver, and magnesium is between larger than 0% and 90%.7. The organic light emitting diode display panel according to claim 2,wherein the second portion is formed from magnesium and silver, andmagnesium is between larger than 0% and 80%.
 8. The organic lightemitting diode display panel according to claim 2, wherein the secondportion is formed of silver.
 9. The organic light emitting diode displaypanel according to claim 1, wherein the ratio of the alkaline earthelement in the first portion is larger than the ratio of the alkalineearth element in the second portion.
 10. The organic light emittingdiode display panel according to claim 1, wherein the ratio of a firstthickness of the first portion to a second thickness of the secondportion is 1:0.5-1:4.
 11. An organic light emitting diode (OLED) displaydevice, comprising: a case; and an organic light emitting diode displaydevice, comprising: a first substrate; a second substrate; a firstelectrode disposed between the first substrate and the second substrate;an organic light emitting layer disposed between the first electrode andthe second substrate; and a second electrode disposed between theorganic light emitting layer and the second substrate, the secondelectrode comprising a first portion and a second portion, the firstportion is located between the second portion and the first substrate;wherein an irregular interface is located between the first portion andthe second portion, the material of the second electrode comprises analkaline earth element and silver, and the ratios of the alkaline earthelement to silver in the first portion and in the second portion aredifferent.
 12. The organic light emitting diode display device accordingto claim 11, wherein the alkaline earth element comprises magnesium (Mg)and calcium (Ca).
 13. The organic light emitting diode display deviceaccording to claim 12, wherein the first portion is formed of magnesium.14. The organic light emitting diode display device according to claim12, wherein the first portion is formed from magnesium and silver, andmagnesium is between 80% and less than 100%.
 15. The organic lightemitting diode display device according to claim 12, wherein the firstportion is formed from magnesium and silver, and magnesium is between90% and less than 100%.
 16. The organic light emitting diode displaydevice according to claim 12, wherein the second portion is formed frommagnesium and silver, and magnesium is between larger than 0% and 90%.17. The organic light emitting diode display device according to claim12, wherein the second portion is formed from magnesium and silver, andmagnesium is between larger than 0% and 80%.
 18. The organic lightemitting diode display device according to claim 12, wherein the secondportion is formed of silver.
 19. The organic light emitting diodedisplay device according to claim 11, wherein the ratio of the alkalineearth element in the first portion is larger than the ratio of thealkaline earth element in the second portion.
 20. The organic lightemitting diode display device according to claim 11, wherein the ratioof a first thickness of the first portion to a second thickness of thesecond portion is 1:0.5-1:4.